Commercial silanes with reactive double bonds represent in general monofunctional compounds with a C.dbd.C double bond, e.g., (meth)acryloxysilanes of the following type: ##STR1## where R denotes hydrogen or methyl and X is, e.g., halogen or alkoxy.
Silanes of this type have, as a rule, low molecular weights and thus, prior to the Si--X hydrolysis and condensation, are relatively volatile compounds, which may have toxicological problems due to the presence of the acrylic groups. During further processing by polymerization or modifying functionalization, these silanes also have the drawback that due to the presence of only one reactive C.dbd.C double bond, only chain polymers can be obtained. Additionally, during functionalization this C.dbd.C double bond, which is mandatory for the polymerization is usually lost. Furthermore, as a rule, there is only a short carbon chain between the double bond and the silicon atom that is capable of forming an inorganic network so that the mechanical properties (flexibility, etc.) can be varied only to a limited degree.